Adhesive and method of making the same



Patented Aug. 6,

PATENT OFFICE,

ADHESIVE AND METHOD OF MAKING '1 SAIHE Earle It. Edson and George F.Mach, Gloucester,

Mass, assignors to Russia Oement Company,

Gloucester, Mass., a corporation of Massachusetts No Drawing.Application February 1, 1938,.

Serial No. 188,098

14 Claims. (C'l. 134-23.4)

This invention is an adhesive for envelope machines and similar uses,having dextrine as a base. It is covered broadly by our pendingapplication Serial No. 120,931, filed January 16, 1937.

' In our pending application we have described a dry mixture havingdextrine as a base, mixed with a dry dispersing agent. This mixture iscold soluble, that is to say, if the mixture is stirred up with water ata normal temperature and allowed to stand a sufllcient time the dextrineis completely dispersed and the whole mixture is suitable for use inenvelope machines without heating.

15 The present invention comes within the terms of our pendingapplication in that it is a dry mixture which is cold soluble andfree-flowing enough in solution to operate well in an envelope machineand also adhesive enough even when prepared with cold water to performthe functions required of the liquid adhesives of an envelope machinebut it is to be put'into solution for the envelope machine in hot waterand contains materials not necessary for a cold solution which areimportant and permit the use of heat in 25 forming the liquid solutionso that the liquid solution prepared with hot water as herein describedfor use in an envelope machine for closing the back seam of an envelope.is a great improvement on all existing products of which we 30 are awarefor the purpose. This invention is rapidly displacing the gumsheretofore used in envelope machines and the like. In thisspecification, we call the product of our invention our new back seamgum.

We take a dextrine which is only partially converted and therefore isonly partially solublein cold water, but nevertheless has hadsubstantially all of its starch changed in its properties somewhat, andadd to it a very large'amount (41% more or less) of dry crystalline ureawhich, as stated in our pending application, has the efiect of causingto disperse in water, dextrine which is not dispersible in cold wateralone.

Unfortunately, however, not every dextrine which answers to theforegoing specifications is suitable for the manufacture of envelope gumaccording to our invention. The dextrine we have found most likely to besuitable is a well-known product made by Healey, Seaver Company and soldunder the name Fineco. This is a partially dextrinized fiourhaving apolariscope test of about '7 and a solubility of about 28% in a.solution. A determination of this polarity value 55 is made by mixingfive (5) grams of dextrine with water, so that the total volume ofsolution is one. hundred cubic centimeters.- The solution must be madeat a temperature not sufficient to cause a swelling of any insoluble orincompletely converted starch which exists in the dextrine being tested.After mixing the dextrine and water, as above described, the solutionmust be periodically shaken for a period of one hour, more or less. Thesolution is then filtered to remove the insoluble portions and thefiltrate is filled into a 100 mm. observation or control tube.

' This filled'tube is placed in a saccharimeter (we prefer the Bauschand Lomb saccharimeter) known as instrument #487, which contains aLippich double prism polarizer with adjustable half shade angle and theVentske scale based on the Bates-Jackson conversion factor of- 34.620

' for a normal weight of 26 grams of sucrose. A reading is then made ofthe degree of rotation with the solution at 20 C. Fineco is made byv theaddition of a catalyst to the fiour and the application of heat andsubsequently buffed with a suitable alkali, such as sodium carbonate, soas to be only slightly acid. Substantially every particle of flour issuitably changed by the treatment to some extent though only about 28%has become soluble in cold water.

Almost all Fineco will be suitable for the making of our new back seamgum but'not necessarily so owing to the extraordinary variability ofdextrines.

Accordingly, before manufacturing our new back seam gum. in largequantities it is advisable to test the Fineco or other dextrine bycarrying out the manufacture of back seam gum as hereinafter described,but in a very small quantity. When a small sample of back seam gum hasbeen produced and made into a solution according to our invention itshould be allowed to stand from one to four days to see whether itremains mobile and fluid or whether it has become pasty, If the smallliquid sample has become pasty, even after-four days, it isunsatisfactory for use in our new back seam gum and should be rejected.

The test may be made as follows. We make an intimate mix having thefollowing composition:

. Grams Fineco, or other dextrine to be tested 150 Crystal urea 60Powdered citric acid U. S. P 4.5

. Powdered sodium fluoride .75

This intimate, mixture is now stirred into '15 grams of water at atemperature of 200 to 212 F. There will be a substantial temperaturedrop,

- to manufacture the new back seam gum in quaneven below 170 F. Theliquid mass is then elevated to a temperature of ITO-175 F., at whichtime heating is discontinued. The liquid mass is then cooled, agitatingwhile the cooling is taking place, until the temperature has dropped to70 F. The liquid mass is then poured into a suitable container andsealed against the atmosphere. This sample is then allowed to remain atroom temperature for a period of four days or longer and if at anytimewithin the four days the liquid mass begins to show serious lack ofmobility and fluidity, then the dextrine used is unsuitable for ourinvention.

However, as above stated, almost all Fineco will be suitable for our newback seam gum. Other dextrines which have been partially dextrinized sothat almost every particle of flour has been suitably changed bytreatment may, however, be used but they should only be used aftermaking a test in accordance with the method hereinbefore described.

Having selected a dextrine which is suitable by the above, or any othertests, we may proceed tity as hereinafter described. 7

We intimately mix, with suitable equipment, the following composition:

, Pounds Fineco, or other suitable dextrine 1000 Crystal urea 442Powdered citric acid, U. 8.? 84.25 Powdered sodium fluoride 5.50

The amounts of the above materials are based on the use of bone dryFineco and ordinary comthere should be a correspondingly decreasedamount of the other materials to secure the best results.

This mixture will then be suitable for use as a back seam gum' forenvelope machines. To prepare for use in an envelope machine it istreated as follows:

For the ordinary plunger type machine 100 lbs. of this dry intimatemixture is mixed with approximately 4 gallons of cold water at normaltemperature, say 70 F., in suitable equipment. The mass is then agitateduntil it is smooth, homogeneous and free from lumps. when in thiscondition heat is applied so as to elevate the temperature of the liquidmass to l70l75 F. It would be best for this temperature to be attainedwithin thirty to forty-five minutes from the beginning of theapplication of heat, though not absolutely necessary. It is then cooledto normal temperature, being agitated periodically, and at this time andfor some time thereafter, is suitable for use in the ordinary plungertype machine.

In the case of the rotary machine, the same procedure as given aboveshould be used except that instead of using four gallons of water to 100lbs. of dry mixture, from six to eight gallons of water, more or less,should be used.

It. is ordinary practice in preparing a solution for an envelope machineto cook both a heavy and a limpid, thin solution, suitable for dilutingthe heavy solution to fit the individual requirements of the machine,paper and operator. The thick and thin solutions are both taken to themachine in different containers and the operator uses his Judgment as tomixtures in determining the consistency required for actual use in themachine. This same practice should be used in preparing our new backseam gum.

As stated above, back seam gum may be made suitablefor envelope machineswithout heating the dry gum and water but we have found, and this is animportant part of our invention, that the dispersion of the dry gum inhot water before use in the envelope machine accomplishes the result ofmaking our back seam gum solution more adhesive. It is not easy nor safeto reason too much as to the causes of this butit is a fact that heatingdextrine and urea and water partially decomposes the urea with aproduction of ammonia, thus making the liquid mixture remaining morealkaiine,'and any variation as to alkalinity and acidity of theseadhesive dextrine avoid the undesirable results of changing thequalities of the liquid gum by heating.

In our present invention, however, heating is advised because with thematerials we now use no harm is caused by the-partial decomposition ofthe urea and the liquid back seam gum, instead of being injured, ishelped by the heating.

The proportions of dextrine and urea above set forth are the best knownto us to be used with the average batch of Fineco and should not bevaried materially to secure the best results. The urea should be morethan 20% of the dextrine and less than to secure satisfactory results.However, if the dextrine used is more highly converted and has lowerviscosity than Fineco then there should be diminution in the amount ofurea used and a proportional decrease in the amount of citric acid andwater. The correct proportion of urea and other materials to be used canbe determined by the test of a small amount of the material, say, forinstance, 150 grams, by the test above described. A large proportion ofurea, at least 20% of the amount of dextrine, should be used. The amountof citric acid used can be varied considerably without harmful resultsbut the'amount of citric acid used should not be less than one twenty- Isecond of the amount of urea used or harmful decomposition of urea andtendency to form ammonia with the result that the product is made morealkaline. The citric acid, we have found, will prevent the harmfulresult from the decomposition of the urea and produce, when heated withFineco and urea, a product superior to Fineco and urea alone whetherdispersed in cold or hot water.

Tartaric acid may be used instead of, or mixed with, citric acid, withapproximately equivalent results. If tartaric acid is used, the amountused should be the chemical equivalent of the citric acid,approximately. After many tests we have found that a group of organiccarboxylic acids or their acid salts which are dry at normaltemperatures, the group being made up of citric acid, tartaric acid andoxalic acid, will accomplish the desired result. Many other chemicalswould neutralize the ammonia satisfactorily but would result in aninferior product for other reasons.

Suitable plasticising or softening agents, as

quired by pecul rity of the paper or climatic conditions.

Our back seam gum may also be used in attaching the glassine windows inwindow envelopes.

We have found that seams closed by our, back seam gum are better thanany seams of which we are aware in resisting atmospheric conditions andwithstanding water, dampness and heat. This is particularly true incomparison with seams closed with dextrine sugar gums. Hitherto sugargums have been the material most used in closing theback seam ofenvelopes dimcult to cause to adhere.

Hitherto most easily adherent papers have often been closed bysolutionso'f dextrine alone. Our back seam gum gives a far superiorclosure for all such envelopes so that even as to easily attached papersthere will be great advantage in using our back seam gum so as toovercome the difiiculties of meeting unfavorable at mosphericconditions.

Sodium fluoride may be entirely dispensed with without departing fromour invention but nevertheless it has many advantages and we considerthe use of it valuable. We prefer to use less than 1%.

Our new back seam gum is available for many other uses than closing theback scam -in envelopes. It will be found excellent for many othermachines than envelope machines.

In the claims, the word Fineco is used to mean Fineco which is suitablefor use in the manufacture of our new back seam gum when tested ashereinbefore set forth.

In the claims a suitable dextrine is used to mean a partially converteddextri ne which will answer the test for suitability for use in themanufacture of our new back seam gum when tested as hereinbefore setforth.

In the claims a suitable organic acidic material is used to mean eitheran organic carboxylic acid selected from the group consisting of citric,tartaric and oxalic acids, or an acid salt of one of these acids, saidacidic material being dry at normal temperatures and conditions.

we claim:

1. A dry base for adhesive suitable for use in envelope machines and thelike, comprising a partially converted dextrine which will not becomepasty when tested as described in this specification, urea from 20% to50% of the dextrine by weight, and a small amount of an organiccarboxylic acidic material selected from the group consisting of citric,tartaric and oxalic acid and acid salts thereof, not less than onetwenty-second of the amount of urea used.

2. A liquid adhesive suitable for use in envelope machines and the likecomprising a partially converted dextrine which will not become pastywhen tested as described in this specification, urea from 20% to 50% ofthe dextrine by weight and a small amount of an organic carboxylicacidic material selected from the group consisting of citric, tartaricand oxalic acid and acidsalts thereof, not less than one twenty-secondof the amount of urea used.

3. The method of making a liquid adhesive suitable for use in envelopemachines which consists in mixing a partially converted dextrine whichwill not become pasty when tested as described in this specification,with urea from 20% to 50% of the dextrine by weight and a small amountof an organic carboxylic acidic material selected from the groupconsisting of citric, tartaric and oxalic acid and acid salts thereofand heating in suiilcient hot water to about 170 to 175 F. untildispersed, and allow it to stand.

4. The method of making a liquid adhesive suitable for use in envelopemachines which consists in mixing a partially converted dextrine whichwill not become" pasty when tested as described in this specification,with urea from 20% to 50% of the dextrine by weight, and a small amountof an organic carboxyllc acidic material selected from the groupconsisting of citric, tartaric and oxalic acid and acid salts thereof,not less than one twenty-second of the amount of urea used, and heatingin suillcient hot water to about- 170 to 175 F. until dispersed, andallow it to stand- 5. A liquid adhesive suitable for use in envelopemachines and the like, comprising a partially converted dextrine whichwill not become pasty when tested as described in this specification,urea from 20% to 50% of the dextrine by weight, and small amount of asmall amount of an organic carboxyllc acidic material selected from thegroup consisting of citric, tartaric, and oxalic acid and acid saltsthereof, not less than one twenty-second of the amount of urea used,dispersed in not more than four gallons of water for each one hundredpounds of the dry adhesive.

6. A dry base for adhesive suitable for use in envelope machines and thelike, comprising a partially converted dextrine which will not becomepasty when tested as described in this specification, urea from 20% to50% of the dextrine by weight, and a small amount of citric acid,

'7. A dry base for adhesives suitable for use in envelope machines andthe like comprising a partially converted dextrine which will not becomepasty when tested as described in this specifica tion, urea from 20% to50% of the dextrine by weight, and a small amount of citric acid.

8. A dry base for adhesives suitable for use in envelope machines andthe like, comprising a partially converted dextrine which will notbecome pasty when tested as described in this specificatio'n, urea from20% to 50% of the dextrine by weight, a small amount of an organiccarboxyllc acidic material selected from'the group consisting of citric,tartaric and oxalic acids and acid salts thereof, and less than 1% ofsodium fluoride.

9. A dry base for adhesives suitable for use in envelope machines andthe like comprising a partially converted dextrine which will not becomepasty when tested as described in this specification, urea about 40% toof the dextrine by weight, a small amount of an organic carboxylicacidic material selected from the group consisting of citric, tartaricand oxalic acid and acid salts thereof, not less than one twenty-secondof the amount of urea used.

10. A dry base for adhesives suitable for use in envelope machines andthe like comprising a partially converted dextrine which will not becomepasty when tested as described in thisspecification, urea about 40% to45% of the dextrine by weight, a small amount of an organic carboxylicacidic material selected from the group consisting of citric, tartaricand oxalic acid and acid salts thereof, not less than one twenty-secondof the amount of urea used, and less than 1% of sodium fluoride.

11. A liquid adhesive suitable for use in envelope machines and thelike, comprising a partially converted dextrine which will not becomepasty when tested as described in this specification, urea from 20% toof the dextrine by weight, and a. small amount 0! citric dispersed inhot water. I

12. A liquid adhesive suitable'ior use 'in envelope machines and thelike comprising a partially converted dextrine which will not becomepasty when tested as described in this specification, ureaitrom 20% to50% or the dextrlne by weight, and-a small amount of citric acid andsodium fluoride. dispersed in hot water.

13. A liquid adhesive suitable for use in envelope machines and the,like comprising a partially converted dextrine which will not becomepasty when tested as described in this specificstion. urea from 20% to50% of the dextrine by tion, urea from 20%' to 50% of the dextrine byweight. and a small amount of tartaric acid and sodium fluoridedispersed in hot water.

EARL-E R. EDSOIN. GEORGE F. MACH.

